In this study, a reconstructed continuous current distribution is employed to synthesise circular (one ring) antenna arrays with sparseness characteristics. The authors proposal achieves the reproduction of a continuous current distribution from an expansion in an orthogonal basis, taking the desired radiation beam pattern as target function. To obtain the sparseness characteristics, they employed a density tapering technique that provides the excitations and locations for each antenna element. They report three numerical experiments that show the performance of the proposal and compare it with other methods in this literature.

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True-time delay antenna arrays have gained a prominent attention in ultrawideband (UWB) applications such as directional communications and radar. This paper presents the design of steerable UWB circular array by using a multiobjective time-domain synthesis of energy pattern for circular antenna arrays. By this way we avoid individual beamforming for each frequency in UWB spectrum if the problem was addressed from the frequency domain. In order to obtain an energy pattern with low side lobe level and a desired main beam, the synthesis presented is performed by optimizing the true-time delays and amplitude coefficients for the antenna elements in a circular geometry. The method of Differential Evolution for Multiobjective Optimization (DEMO) is used as the optimization algorithm in this work. This design of steerable UWB circular arrays considers the optimization of the truetime exciting delays and the amplitude coefficients across the antenna elements to operate with optimal performance in the whole azimuth plane (360 ∘ ). A comparative analysis of the performance of the optimized design with the case of conventional progressive delay excitations is achieved. The provided results show a good performance for energy patterns and for their respective power patterns in the UWB spectrum.

The design of a beam-forming network (BFN) for a multibeam-steerable antenna array using Coherently RadiatingPeriodic Structures (CORPS) is presented. In this design, the input ports of the feeding network are optimized usingthe particle swarm optimization (PSO) algorithm. A two-beam design configuration of CORPS-BFN for a multibeamsteerablelinear array is proposed and analyzed. The results shown in this paper present certain interestingcharacteristics in the array factor response, in terms of sidelobe level (SLL) and directivity (D), for the scannablemultibeam linear array and the feeding network simplification for the design of BFN based on CORPS.

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